How do you convert a task into a sub task in IOS ?

Hi,
Is there a way to make a task into a Subtask using the IPAD app ? I usually forward my tasks from different inboxes into Toodledo, and some of them are tasks related to a project and would like to make it a sub tasks - I see you can do it on teh Web version, but am not able to figure out how to do it on my IPAD - which is becoming my primary task management and note taking device.